HOW IT WORKS
GPS (Global Positioning System) uses satellites to send microwave signals down to a GPS receiver to determine their location at that time. In our project, we expect to use a GPS to send real time signals that constantly ping the user’s device to find their location which is then used in the distance over time equation to get their velocity. This velocity and GPS signal location is then used to give the user their current velocity and an estimated time of arrival to their desired location.
We intend to have a variable sampling rate ranging from 5-15 seconds depending on the needs of our system. A variable sampling rate allows the app to keep the user up to date with all the necessary information throughout their ride without the app consuming too much power. A longer journey would not require a higher sampling rate because not much changes in 15 seconds whereas a shorter distance requires more frequent updates of the journey.
The sampling rate also should change based on the distance travelled, the shorter the distance to the destination the higher the sampling rate gets. Sampling will be filtered and processed through use of a kalman filter.
FLOWCHART OF GPS
Description:
The above figure details the specific actions of the system which were explained prior. The figure also briefly goes into the possible directions it could take once we get our GPS signal into a more compatible/recognizable format (or any signal that can be attained for travel needs). Currently, we could take the information from the users’ location use it to send various data to a more complex system managed by the framework the railway operates on. We could also take that information and strategize ways to use it to benefit the customer as they travel to and from each stop. Ideally, we would like to incorporate as many techniques learned in Digital Signals Processing.
Overall, we would like to create this project to learn how DSP may help us create solutions for travel/transit of any form, not just via railways. If we are able to proceed from convenient and efficient networking of railway transit needs, the same project could be used for bus transit, airline transit, and various other modes of mass public transportation in areas of low technological development.
CREATING A SIMPLE GPS RECIEVER SYSTEM USING MATLAB SIMULINK
General GPS Reciever Layout for RF inputs
This fairly complex design is just a basis for what we wish to create, and could turn into a senior project if we wish to fully simulate this exact model (accounts for noise effects, doppler effect, interference, gain control). We want to port a more simple form of this into a block diagram, give it sample signals from a data set, and observe the output when given specific parameters throughout the circuit. Note, that this is an analog model, things could become more simple as we convert to digital at the output of the amplified bandpass.